TNG is a great place to start too! It's more matured and gets into the philosophy of trek more thoroughly. Although, fair warning: it's pretty episodic as well. Like TOS, there will be a handful of characters that show up every so often or events that change things, but most episodes' stories wrap up within the 50min runtime.

In both cases, it was largely so that people could watch stuff out of order back then and not feel lost.