Here are some you might not have heard of....
Ruins of Maraqua..... if your 5-year-old learns the actions of the game, it should be pretty easy.... and its labeled easy in the first place. and its a "puzzle" game... always good for kids
A non-flash alternative might be kacheek seek... although that does tend to get boring relatively fast.....
If your child understands the laws of gravity at all, the new Petpet cannonball could be possible... *then of course, if your child gets good at that game, you could try Bouncy Supreme*
Bumper cars is a little hard, but i think is very intresting, especially for a young one who would probably enjoy smashing cars together.
While "Escape from Meridell Castle" is labeled "hard".... i know that lots of those "Mario" like games are easy to learn fast, and though your child might not be able to get past..say...level 5, it still might be fun.
Ice Cream Machine is pretty simple... since the charactor just has to avoid the ice cream flying at her...... and its marked "easy"
and lastly.... turmac roll. super easy..... super very really easy, and addicting. and fun. yes.....
so yeah.... there are some games that people probably wouldnt think of off the top of their heads..... hope that helps!
once again, they are:
Ruins of Maraqua
Kacheek Seek
Petpet Cannonball (then maybe bouncy supreme)
Bumper Cars
Escape From Meridell Castle
Ice Cream Machine
Turmac Roll