We are here because of a perfect sequence of events throughout the 13.7 billion years the Universe has been in existance.
Without stars the matter that we are made up of would not have formed, without the late heavy bombardment there would be no water on the planet, without the iron core of the earth there would be no volcanic springs under the sea for microbial bacteria to form from the basic amino acids and proteins delivered by asteroids nor would there be a magnetic field to protect us from the solar winds, i could go on all day but the fact we are here is purely down to chance and a perfect sequence of MILLIONS of events throughout time.
Why the universe itself is here (or multiverse if you are up to date on physics) is going to be a mystery forever in my opinion, until we develop the technology to either create a big bang or look outside our universe into hyperspace we simply will not know.
I dont think we are the only thing "here" either, if you look at the sheer numbers theres 200 billion stars JUST in our galaxy and its not a big one, theres 100 billion galaxies, some with 1 trillion stars, the amount of planets out there is unimaginable so out of the say on average 500 billion stars per galaxy there is potentially planets in the goldilocks zone (planets that can hold liquid water the key to life) in x 100,000,000,000 you can imagine theres probably at least 10,000,000,000 earthlike planets, all it needs is for 1 of those to have a moon and water and have gone though a roughly similar cycle to what our planet has there is bound to be more things "here"
Some people believe in "Gods" which is fine but too me if you look at religion and human existance it only accounts for a spec of time (few thousand years) in the existance of what we know for a FACT has been here for 13.7 billion years, our solar system is 5 billion years old, what was "God" doing for the first 4.99 billion years that our solar system existed if he made everything in 1 week?
This thread and my post alone could go on for hundreds of pages lol Faith is a VERY powerful tool that has been used to shape our time on earth but scientific fact for me is far more powerful as it provides concrete answers with evidence to back them up. You can ask a religious person where man came from and they might say God but they will never be able to explain why there is 100 billion galaxies or why we are made up of the same 92 elements that Stars, mountains, water, air, animals, plants, metals and everything else in the universe is made of
Our lives are a blip A TINY BLIP in the scale of time we live (if we are lucky) to 60-80 years on average, the universe has been here 13.7 billion. we are SOOOO insignificant its amazing yet we think so highly of ourselves as a race that a lot of people think if there are Aliens they want to come and see us and give us technology and advanced medicine, when in realism we are minor and have only made 1 probe that has taken 30 years to get past Pluto if something could transverse space to get to us (bearing in mind closest star Proximus Centuri is 4.2 x 900,000 kilometers per second away) we would look about as significant to them as bacteria as anything that can travel across space in less than a lifetime will be so advanced it probably wouldnt even notice the human race