Why does crypto move all together?

My new but not so new to crypto self is trying to grasp an understanding as to why coins move in the same direction, what to me looks like following btc/eth. This graph here is just some coins that I like to watch and I am coming from a perspective that everything is it’s own project and community and investment. So why does it all follow suit? Is that how it’s always been and I just haven’t noticed? Or is it just the way the market is now? I’m hoping here just to get some advice or experience wise explaining.

https://imgur.com/a/SDHHjwG