Mission on earth (In Buddhism)

Your mission is to be happy.

The long term goal associated with this mission is attaining Nibbana (permanent happiness). It might take multiple births, maybe even aeons to achieve this.

The medium term goal would be to try to achieve: at least stream entry for Theravada and strong cultivation of Bodhicitta for Mahayana.

The short term goal would be to try to achieve and maintain happiness in this life and future lives (which includes avoiding unfortunate rebirths).

This short term goal is described in the Ittha Sutta:

Long life, beauty, status, honor, heaven, high birth: To those who delight in aspiring for these things in great measure, continuously, the wise praise heedfulness in making merit.

The wise person, heedful, acquires a two-fold welfare: welfare in this life & welfare in the next. By breaking through to his welfare he's called prudent, wise.

For lay followers, there is plenty of advice on achieving the short to medium term goals in the Gihi Sutta (or Discourse to the Householder), Sigalovada Sutta, Dighajanu Sutta and Anana Sutta. The minimum training rules imposed on lay followers are the five precepts.

For those in a hurry to Nibbana, there are the more advanced training paths of anagarika (sort of a pre-monk or pre-nun), novice monk or nun, and fully ordained monk or nun.

I won't mention saving others at all (i.e. the Bodhisattva ideal), but instead take a look at for example the background story to verse 5 of the Dhammapada.

You wrote, "everyone has a different mission, a specific reason to be here" and maybe this story is a Buddhist version of that: i.e. these specific women had a personal feud, which continued through rebirths, until eventually they learned to stop feuding.

You could phrase that as saying that their "specific reason to be here" was to learn that "hatred could only cause more hatred, and that it could only cease through friendship, understanding and goodwill".

At the end of the discourse, the ogress was established in Sotapatti Fruition and the long-standing feud came to an end.

Simply put, your mission is to be absolutely happy, happiness that does not depend on circumstances but comes forth through your own Buddha nature manifesting. At the same time, enabling others to do the same. In this Saha world which is full of suffering and negativity, in order to do that one needs to "demonstrate" to others how.

This is where our desires and social roles come into play. To create value as a family member, doctor, teacher (pick your profession), to be able to create value in other ways in society centered on Buddhist practice, etc is the "role" one plays to display the immense power of Buddhism and lead others to absolute happiness. Buddhism and daily life are one and the same.

To say that our mission as Buddhists is to escape Samsara (this world) or in other words to escape from the cycle of birth and death (wrongly interpreted as nirvana) is to be selfish. That is not the way a Buddha or a Bodhisattva thinks.

Shakyamuni Buddha says in the Expedient Means chapter of the Lotus Sutra - "At all times, I think to myself: how can I cause living beings to gain entry into the unsurpassed way and quickly acquire the body of a Buddha?"

Note that Lord Buddha says that everyone can become a Buddha, and he says that at all times he exerts himself to enable others to become like him.

In short, to enable ourselves to reveal our Buddha nature and helping others do the same is our true mission as Buddhists.

As of my understanding,

If you are practicing Buddhism, yes your goal should be ending the 'Sansara'.

Buddhism describes Sansara is a very painful journey which we are roaming without knowing that. Therefore ending Sansara is a fair statement in that sense.

I don't know any Sutta or speech which load Buddha preaches about anything else but ending Sansara and it's brutality.

For analogy, in war time, the ultimate mission of the military is to win the war. But to achieve that mission, many sub-missions would also need to be completed successfully: winning battles on various fronts: intelligence, logistics, politic, economic, etc. Similarly for Buddhism, to successfully defeat Mara's army and put an end to Samsara, there're many "sub-missions" to be done. A lot of these like observing the precepts, practicing loving-kindness, generosity, etc. are also common missions across religions. Ven. Bodhi in his "In the Buddha's Words" did a good job in organizing the Buddha's teaching into systematic and gradual Dhamma "missions": Happiness visible in this present life, the way to a fortunate rebirth, mastering the mind and the Path to Liberation, attaining the Light of Wisdom, and ultimately, Final Liberation.

In Buddhism there are different levels of motivation, on the "lower" levels of motivation are the range of goals to escape suffering for oneself only.

In "higher" scopes of motivation there is the goal to not only escape suffering, but to help others escape as well.

The "highest" scope would be a goal to help all beings escape suffering (Bodhichitta)

I put the words lower, higher, and highest in parenthesis as they are what I believe to be part of a false critique the mahayana/vajrayana holds of the other schools. In reality the other schools are a prereq to even attempting Mahayana practices in most cases. I don't like or agree with the critique but it helps to explain.

The Bodhisattva vows and the goal of the higher schools could be considered a mission. But is not a requirement in Buddhism.

This is going to be one of those Zen answers that tend to irritate people.

When I asked my teacher this question, he said something like:

Mission, hmm... You want to be told what to do? Why?

This is not meant as teasing, it's a sincere invitation to sit and contemplate your personal answer to the above.