Are you guys really that dense?
The earth is billions of years old developed from single cell organisms that reproduced. There are more organisms on the planet every generation than there were the last.
Then you want to talk about a practical argument?
All of the people remember multiple past lives where they were some type of nobleman. No one ever says "back when I was a protozoa".
Reincarnation is just more religious bullshit with no empirical evidence. So sorry.
EDIT: I see you said multiple planets.
I see so I can just make up random shit and live my life by that. I gotta try that.
I'm going to start praying to my royal, cosmic twin living on the third earth just 15 parsecs outside of Alpha Centauri and tell him that I want a mind meld so I can gain access to the universe's cosmic Karma field, thereby becoming spiritual royalty.
Yeah there isn't empirical evidence for it, but it's an interesting way of looking at things, especially from a quantum perspective. It's a refreshing way to look at death after having heaven/hell shoved down my throat since childhood. It's not perfect, but it's more reasonable than most religious beliefs.
There are certainly holes in the idea of reincarnation/rebirth but your arguments against it are sort of weak.
Your first point about growth and evolution doesn't really prove anything either way, the quantity and complexity of life certainly grew over time on the planet (and likely every other planet with life on it), but that doesn't prove that their consciousness was limited and unable to continue after their bodies died. Evolution certainly catches a lot of religious beliefs with their pants down, but it doesn't prove anything about what happens after death for the consciousness.
Why would we remember our life as a protozoa or simple life form, there are hardly any senses through which to experience the world at that level, it would be an almost unconscious state. In fact, we don't seem to remember anything at all before our birth into our current bodies, but does that imply that we were non-existent before that point? Your point seems to be that people who talk about their past lives always talk about being human, personally I think they are a bunch of bullshitters who want attention and they don't remember shit, and considering that you think reincarnation is bullshit you feel the same way, right? IMO they are obviously lying, their testimonials don't prove anything.
And I'm not sure what your beef is with the idea of reincarnation being a universal trait instead of being limited to a single species/environment/planet, in fact diversifying the way that you come back that would be a requirement for equilibrium to be maintained if reincarnation were to occur.
I won't argue that there's empirical evidence for reincarnation, but I will say that it's one of the most reasonable religious/spiritual ideas I've come across if you strip away the superstitious interpretations of some cultures and religions.