Life of Buddha, to be taken seriously?

After 50 years of mindfulness meditation practice and receiving novice ordination some 30 years ago (full ordination was not available in Canada back then), I can say with certainty that it is meditation practice that counts the most in the Buddhist teachings. From this point of view, the most important part of Buddhism is the Buddhist psychology of meditation, even though it is incomplete and offers almost no explanation as to why meditation works. The life of the Buddha tells us little about meditation. There are many gaps in the "logic" of Buddhism. I sincerely hope you will take up meditation practice anyway.

It's like the bible. Some more moderate believers see it as metaphorical whereas the more hard core believers take the whole thing literally. Personally I think the whole thing needs to be taken with a grain of salt. Nobody can prove any of it is real just like they cannot prove the bible. The dangers of taking such writings literally leads to fanaticism and violence which can be seen all throughout history.

I think that the story of the new-born baby walking and talking might possibly come from (or is most commonly found in) the Jataka tales (and/or the Buddhavamsa), and not the suttas.

Conversely I think the suttas tend to be more "realistic", as you put it.

There's only one sutta that I know (but there may be others) that mentions a supernatural birth, which is MN 123 ... but, and I don't know why, MN 123 isn't translated on Access to Insight, nor on Dharmafarer. Perhaps neither translator found that sutta among the most important to translate?

Anyway you might prefer to read, might find more benefit in reading, the suttas than the Jataka tales.

One of the anthologies of suttas, which people on this site recommended, is In the Buddha's Words ("An Anthology of Discourses from the Pali Canon, Edited and introduced by Bhikkhu Bodhi").

Are these stories, therefore, meant to be understood as metaphors, or are they believed as fact?

If you are talking about Jataka tales, then see for example the answers to the topic, Does Theravada Buddhism accept Jataka Stories?

Some popular anthologies/stories of the Buddha's life start with the Four Sights and the Prince's decision to leave home, rather than at birth.

The Pali canon was put down in writing hundreds of years after the parinibbana of the Buddha, having been transmitted orally for that time. If not the message, then at least the presentation of the message was altered to suit rote memorization (one reason why some perceive the canon to be a 'dry' read).

It is good to be aware of the fact that the Digha Nikaya was likely an introduction to Buddhism for the wider brahminical/Hindu society of the time, hence the mix of very 'clean' suttas with ones that discuss gods etc.

Interestingly, though a later creation (likely 100BC), the Milinda Panha offers an explanation that all these jumps that the Buddha and his disciples make to Sakka's realm etc are only mental episodes - a reasonable explanation imo, given the prevalence of that imagery at that time, as well as the power of the mind to see that which it has been concentrating on for long periods of time.

Even in the canon, there are suttas where the Buddha addresses monks who have come from different schools, wherein he discourages them from staying engaged with beliefs they had from their times before joining the Sangha (with Samkhya philosophy in MN1 for example), so it would be no surprise if later, after his parinibbana, new devotees brought a level of their own baggage to the texts.

Personally, I don't mind that a 2500 year old expounding of a world view has a little embellishment and degradation in it - expecting otherwise would be misunderstanding how humans tend to act, and a disservice to the understanding of anicca!

The Dhamma the Buddha declared was stated as verifiable in the here and now, and for the most part the canon is very repetitive and consistent for the main message. If you come across ideas that cannot be verified, or seem to be one off entries in the canon, it is fair to question them, especially if they break with our now basic knowledge of science (newborns walking etc).

If a part of a text does not directly discuss the Dhamma, see if it points to aspects of the message indirectly. If you can't see anything, enjoy the story!

(though I wouldn't be too critical of the austerities part, the Samana movement seems to have had some pretty determined people in it at the time, and in SN 56.11 (the first sermon), the discourse is specifically about staying away from the extremes of sensory indulgence and self mortification, meaning austerities likely played a big part in the Buddha's path to enlightenment)

MN 123 describes the Buddha's physical birth; standing, walking & prophesying about himself. This contradicts MN 64, which states a new born child has no mental conceptions of self or identity.

Since there is a contradiction here & since we know from reality that new born children cannot mentally construct words about themselves, we can be confident the birth story of the Buddha is false & a form of religious mythology.

MN 123 is of a tiny genre/style of suttas similar to the later-day Jataka, Apadana & Buddhavamsa stories. Therefore, it is highly probable the Buddha did not speak MN 123 & that MN 123 was a later-day composition. These Hinduistic ideas eventually contributed to the extinction of Buddhism in India because they reinforced/supported Hinduism & diminished the uniqueness of Buddhism.

Other stories, such as seeing the four signs of an old, sick & dead man and seeing a monk and then sneaking out of the palace, also appear to contradict what is written in the suttas, which report Gotama was well aware of aging, sickness & death in the palace and that he left the palace with full knowledge of his parents, who had tears streaming down their faces.

Three months after Shakyamuni's death the first Buddhist Council was convened. There was no written method to record his teaching so a group of monks, many with eidetic memories, were chosen to commit the Buddha's lessons to memory. This was the system used to pass down his teachings for hundreds of years.

So, that said. it remains rather unsurprising that certain liberties were taken with the "facts" in order to facilitate a good story. The type of story that would survive hundreds of years of interpretations. When I see what appear to be outlandish statements I try to focus instead on the idea or feeling they are trying to emphasize with the casual approach to reality.

Especially in various koans this approach becomes very useful. I see the exercise as a further lesson taught to us by the dharma. Not as some attempt to mislead.

I hope this helps you. I encountered the same concerns years ago as I sought refuge in the dharma. In fact, to me this is part of seeking refuge ... how willing and successful are you at parsing the kernel of knowledge gleaned amidst the so-called chaff? Namaste my friend.

the Buddha taught that there is unsatisfactoriness in this world and the way out of it which is more systemised as the 4 Noble Truths.

If these stories help you understand unsatisfactoriness and help you come out of it or inspire you in any way to practice and strengthen your faith, by all means use them. If not leave them aside without outright rejection and concentrate on what appeals to you.

What is most important is you follow the Noble 8 Fold Path divided into the 3 Fold Training which results in understanding the 4 Noble Truths.