Is samsara real?

'Samsara' is described in SN 22.99 as continuously attaching to the aggregates as "self".

'Recollecting past abodes' (not "lives") is described in SN 22.79 as recollecting how in the past the mind misunderstood aggregates to be "self".

When Buddha used 4th jhana recollect past abodes ("pubbe nivasa"), the Pali used translated as "birth" is jātiyo, which means social or self identity; or, simply "self".

That your mind continues to attach to the five aggregates as "self" shows samsara is real.

That you think 'samsara' means 'reincarnations' ('transmigrations') rather than attaching to the five aggregates as "self" in the here-&-now shows samsara is real.

That you 'wander' ('samsara') to this chatsite asking questions about things you wish to understand shows this samsara (wandering) is real.

According to Mahayana, the meaning of Dharma is metaphorical or expedient ("upaya") - and you are taking it literally.

In my understanding of Mahayana, -- and it is very clear to me that this is how the original Buddha meant it as well -- things like reincarnation, liberation, karma etc. all refer to informational, psychological, and ethical aspects of reality - and not to some fairy-tale fantasies.

According to this interpretation, there is no literal "afterlife" (it's not even a concept that ever occurs in Buddhist texts!), there is cycling of forms - generation after generation, carrying same patterns along in a self-perpetuating way. There is no "cosmic law that liberates" and "is eager" - there is natural evolution towards greater awareness. (In the modern science these natural laws are beginning to get described in the emerging discipline of "biosemiotics")

So if we look at it from this perspective, why would the natural laws care about "beings be given ability to observe and realize the truth about samsaric worlds"?

Regarding the chicken and egg problem you are describing (that, for the sentient beings to get serious about Liberation, they'd need to clearly understand the problem, but according to Buddhism a clear understanding of the problem is only possible at the very end - almost at the time of Enlightenment itself, which makes it a vicious circle) - this has unfortunately been an issue with Buddhism all along throughout its history. Because the root cause of the Problem is Ignorance, there is no easy way to approach this issue.

Over the centuries of experimenting, different schools developed different methods, ranging from trying to explain everything with the hard logic upfront - to using informal hints to carry the gist of the Vision across - to asking the student to take it on faith and focus on practice until they get clear enough to start seeing it for themselves - to feeding the student with expedient fairy-tales as a child-friendly carrot effective as a temporary surrogate for the actual understanding.

So your concern and confusion is completely appropriate and well-based. Unfortunately, there are no easy answers to this (outside of the tongue-in-cheek "trust Andrei he knows what he's talking about") - or else you are on your own in this sea of doubts, trying to figure out what is what from the all the million voices screaming at once.

Fortunately, Buddhism does not require you to understand all this in order to get the basic ground under your feet and start making meaningful progress. All you need to do is understand the following basic framework:

Pain feels bad, peace feels good - at the end of the day this is what really matters. Stupid actions lead to inner pain, smart actions lead to inner peace (long-term; short-term there could be temporary roundabouts). Stupid/painful is by its nature is polarized, black-and-white, selfish, greedy, and leads to conflict. Smart/peaceful by its nature is all-encompassing, sees things from all sides, altruistic, and leads to reconciliation of positions. Start acting smart and don't act stupid and soon enough you will see the benefits for yourself. There is no need to be Enlightened to understand that if you create peace, you will get peace and if you create pain you will get pain. - this is sort of self-evident and is all you need to practice Buddhism.

Basically, the above was the gist of the answer Buddha gave to the confused folks as depicted in the Kalama Sutta. Don't worry about "Samsara" and other metaphors.

To avoid all evil, to cultivate good, and to cleanse one's mind — this is the teaching of the Buddhas.
_{- The Dhammapada: Chapter 14}

The law of Kamma is that one’s actions will have consequences. A natural extension of the law of Kamma is the validity of the rebirth process (samsara). It is because the result of a kamma can bear fruits in this life or in future lives. We will continue to acquire kamma seeds (good or bad) that can lay dormant for a long time until conditions become right for it to germinate, in this never-ending samsara. The only solution for this predicament is to come to Sotapanna (stream entrant) stage. When one gains the knowledge to comprehend how suffering arises and how one can eliminate future suffering, one will get to know of the causes that need to be eliminated to overcome otherwise inevitable future suffering. This is knowing how anything in this world (pancakkhanadha) arises due to causes. And whatever arises, it matures with time, gets altered in unexpected ways, and then inevitably gets destroyed. A living being arises due to causes, and when the underlying cause or the fuel is spent, the living being dies. But the process does not stop, because the being had acquired new causes (new kamma) during that life or in the previous lives.

Thus samsara or “transmigration”, can be said as this incessant journey of thoughts based on birth and death. Every moment a countless number of thoughts arise and cease in the mind. This countless volume of thoughts is referred to as “ogha” (flow) in the Buddhist literature. Everything that gets caught in the ogha (flow) gets carried away with the current of the water flow. Once caught in the current of the water flow, there would be no escape from it. It would be very difficult to cross over to a shore. In accordance with Buddha’s analysis, a birth of a thought goes through five stages; i.e. rupa (forms), vedana (feelings), sanna (perceptions), sankara(formations) and viññana (consciousness).

Vinnana is how one sees the world at any given time. It is awareness, but it gets coloured by our feelings, perceptions and intentions (sankhara). You and I are at different levels of Vinnana depending on the level of our knowledge of dhamma and its application. The difference is in seeing the world thru dhamma. Normal humans’ Vinnana is conditioned by our accumulated sankhāra with ignorance as condition. When we die, our kamma seed has our habits (gati) and cravings (āsavas) embedded in it. When the next life arises, with sankhāra as condition, another viññāna arises in the new life. Thus it can be said that this very life will not be the end or the start. It’s a circle. Until one eradicates the reasons to be-come, which is the thirst, s/he will live, die and come back and die again, so and so forth. This whole process or the journey is called Samsara.