2 Cents: I used Maple for my kids blocks.
They were finished with beeswax+mineral oil. Most of them are still in pretty good shape.
I made them in 1961
I still get to play with them sometimes, mostly with Grandchildren.
New ones (more kids need them than in 1961) are Cherry, with same finish. Not as hard / dent-resistant, but they're pretty. Fortunately, Cherry grows on our place. Easy to carve, too. Each new kid has one Cherry block with their name one side, and their birth date on the opposite side.
You won't be sorry that you put some effort into making blocks for kids.