The human race is actually quite strange

The human race is actually quite strange. We do so many things on a day-to-day basis without actually questioning it. For example, imagine visiting Earth for the first time to find strange beings just slapping their hands together simultaneously.
“Wow, thanks guys. I feel really honoured that I was able to make you basically hit yourself a couple times for me.” Do you get why that’s pretty weird? If you haven’t realised already, I’m talking about clapping. Did someone just decide that that was a great way of showing your appreciation and everyone else was like “Sure, why not?” It sure does seem like it. Especially as the entire population seems to mutually know what it is.
If aliens ever came to Earth, I would be surprised if they weren’t concerned.
But that’s not all. What’s make me question my existence even more is sleeping.