Christmas for kids

My son will be 1.5ish around Christmas and it got me thinking. I'll obviously teach him about Jesus and the real reason for Christmas but... what about the other Christmas festivies..

How does Santa fit in? Is it ok to give him some Santa believing years?

What about this elf on the shelf ( don't know much about that but I guess that's a thing lol).

How much is just fun and how much is going too far?

I have no answer to this and won't really have to deal with it until he's at least 2... I just want to make sure he know Jesus is the reason for the season and not Santa but I also want him to have fun with festivities.

What are your thoughts on this?