I would put his age 3 or slightly more. 2 years old and that big and riding a bike is little much. But a narrowing down of the bikes age would be good to have.
I agree with GregNH, two is too young for the tricycle photo, 3 or 3 1/2 I’d say. The outside diaper photo looks like 2 or a little more, at most 2 1/2. People did not keep toddlers in diapers as long in those days, usually.