From the theories I know of, not many are infinite. -The ones put forward by serious physicists that is.

For the SciFi fantasy ones though, anything's cool, but then most aliens in popular SciFi are human shaped, just with weird skin and a funny head -_-

That sorta reminds me of a song but the song lyrics are on a smaller scale:
"For billions of years since the outset of time
Every single one of your ancestors survived
Every single person on your mum and dad's side
Successfully looked after and passed on to you life.
What are the chances of that, like?
It comes to me once in a while
And everywhere I tell folk it gets the best smile."

Alternate events? hmm.... Either Washington established a monarchy instead of surrendering the presidency OR Napoleon had succeeded in uniting Europe... maybe both, why not.

We wouldn't have shitty Coldplay songs like Viva La Vida.

That's true, but unfortunately they'd compensate with another shitty song

So then it's settled we go back in time and eliminate Chris Martin and in turn stop the birth of Gweneth Paltrows baby Apple who will one day become the greatest fascist dictator the world has ever seen.

so universe is just like people

The dinsaurs were never wiped out and evolved into intelligent bipedal creatures then invented the internet and developed a community about web comics named after an inebriated waterfowl cousin of theirs.

That's not alternate, that's reality.

The trick is; how do we keep that pesky human out? You know... That one guy. Kyup...
Ah, best not say anymore, he already knows faaaar too much!

I suggest a few chemtrails tomorrow to cover our tracks.
Maybe a vaccination and some more fluoride?

I think it would be interesting to see what the overall outcome would be if the dinosaurs had survived being wiped out and if evolution had taken place

In a few instances, you can do this type of thing with the Civilization games AND Spore. Too bad Spore, while a very, very fun and addicting game, doesn't expand on the entire Civilization style-gameplay.