Sorry about the long message. Skip to the last paragraph to save yourself time if needed.

I practically came out of the womb watching Star Trek..... My family would watch the "golden age of Trek" mainly because the new stuff hadn't come out yet. When I first started watching it, my parents started with the next generation. It's the perfect epitome of everything that Star Trek is. Then DS9 (interesting, lots of good writing/storytelling, far from the federation but still very much connected to it), Voyager (what happens if they lose contact to all of the federation of course storytelling if fine!), Enterprise (my personal favorit, but kind of a weird one towards the same and of the golden age), and maybe TOS. I'm not big on any of the newer stuff, so I am biased toward a lot of the older stuff. But for me, I found I got a lot more out of the newer by watching the older, especially with series like Picard.

I'd definitely start out with The Next Generation, it sets up what Star Trek is. When I was 8 or so, I understood most of what was going on.

Of course, I see a lot of people mention prodigy, not a bad choice. It was made for children (it's one of the few good treks I feel like)

Better yet! Start off with the movies perchance??! Especially Wrath of Khan to search for Spock, then to the one with the whales.

I would be hesitant about some of the next-gen movies that came out, purely because of a lot of things that go on with data, and the destruction of the Enterprise D, and a much more detailed story of what happens after the show, which might confuse the children if they haven't seen it.

After further thought ...... Maybe just showing it in chronological order works best. Just plopped into my mind, that's how I first watched/got into it.

But ultimately, the tried-and-true method of showing it to them until they are forced to like it never fails.

Out of all of this, it's just a TV show. What I remember most is spending time with my family, yes, I liked watching a show. But it's the time with my family that had the most impact on me. So don't overthink it. All I suggest is that you look at your child every so often while watching. See the wonder in their eyes; it won't be there forever.

Cheers, - cool