Well modern man is relatively young in evolutionary terms. Evolution is a funny thing there's no exact time frame for an advanced civilisation to evolve( I dont even count us as very advanced)
While you can consider that modern man may only have been evolving for maybe 10 or 20 million years or so and that that could have occurred at any time over a period of maybe the last 250 million years of earths existance, to get from the first self replicating compounds to some sort of small rodent or something capable of evolving into man (or equivalent) took several billion years, not only was life evolving during that time but it was also affecting the environment to support later evolution and In my opinion it's quite possible that that stage has to be in the order of billions of years.
As for other universes and dimensions well there's theories on ETs UFOs etc that they actually come from another dimension! There's a lot that we can't comprehend when it comes to space and time!
I love sci-fi and reading UFO stories and stuff but even though I accept some people have seen some strange things I am yet to be convinced we've been visited by something else.
To use my phone in the car I deleted all my German contacts, it's now Hans free.