Are you suggesting plants aren't successful? More importantly, from where do yo derive the false notion that evolution has a necessary or predictable direction?
Why is there sex?
Even bacteria and viruses engage in DNA exchange and insertion. Where is there not sex?
That's not sexual. It is called "asexual reproduction". And surely you knew that -- it's in any biology text.
Cartoon idea here:
Frame 1. Cartoon bacterium (semi blob, no flagellum or anything.)
Frame 2. Cartoon of cell division beginning.
Frame 3. Cartoon of almost finished cell division, with just a small "bridge" or filament of protoplasm left to connect the dividing cells.
Frame 4. Two cells, next to each other.
Frame 5. The same two cells, with a one cell asking the other:
"Was it good for you?"
Cheers!