How many satellites are there, and which are there on each planet?

If you count all the little nuts, bolts, loose wrenches and pieces of demolished satellites as satellites, then there’s a whole lot of junk floating around Earth. Thousands of pieces that pose a hazard.
spacejunk

Around the moon we have about three functioning spacecraft but have launched far more than that that have, over time, gone dead – perhaps crashed to the surface of the moon. Then we have the odd Juno spacecraft around Jupiter, the voyagers I and II and so on. We’ve put more space junk up there then anything else. This is a fairly accurate artist’s rendition of space junk around Earth.

The Russians have put several probes on Venus, the Americans and Europeans put a probe on Titan, we have probes on Mars, we flew a probe by Pluto and orbited Saturn for a long while before crashing deliberately. We presently have, as mentioned, the Juno spacecraft around Jupiter. We have hundreds of functioning satellites in orbit around Earth.

Does anyone believe in extraterrestrial life? If yes, why? If no, why not?

Pretty much all of science and scientists in the world believe in extraterrestrial life, even though no evidence of extraterrestrial life has ever been found to date. Why do scientists believe in extraterrestrial life? Simply because there are billions of stars in the Milky Way galaxy and billions of galaxies in the universe. Somewhere it is highly likely that extraterrestrial life exists. It is even possible that extraterrestrial life of some form or another exists on Titan, within our own solar system!

Perhaps human race's home was not Earth in the first place, but in another planet, and we came here to prevent extinction

Mechanical, intentional interstellar travel is unlikely since the distances are far too great to imagine. The best anyone could achieve is interplanetary travel within one’s own solar system. Therefore, if we pass the buck and say life didn’t start here but started somewhere else and arrived here, it would have had to arrive on a rock or asteroid as a microbe and somehow survive a fiery entry through Earth’s atmosphere and it would have had to survive the vacuum and temperature extremes of space. If the rock came from outside the solar system it would have had to survive a long, long time.