And, yes, it goes over the top at times. The River Phoenix sequence is a bit contrived with Indy receiving all his trademarks in one adventure.
Actually, that idea is more plausible than it would seem to be for this reason: if I'm a young Indiana Jones, and this amazing experience just happened to me, why wouldn't it make a lifelong impression? Can we not all relate? (Here's a hint - we all like Star Wars a lot)