TikTok is imho one of the closest approximations of a marketplace of ideas, or a penny-university. Every topic under the sun is talked about (even if TikTok tries to censor a bunch of topics), you have various experts from their fields giving insights into their daily lives (like snippets from the daily life on an arctic base) or short tutorials (how to draw an owl kind of stuff), but also discussions about philosophy or how to deal with daily life (e.g. how to declutter your space if you are depressed, or how to arrange furniture). And unlike e.g. YouTube's recommendation algorithm that makes everything seem bland because it only shows you stuff that's like stuff you already know, TikTok's algorithm keeps exposing you to new things tangentially related to what you watched/liked, so it's more like drifting though an ocean of videos, with new stuff happening all the time.
That said, TikTok should totally be enjoyed in moderation, and there are some places on TikTok you should avoid. If you linger on videos showing teens twerking, you will get more videos of teens twerking; and it's easy to see how that kind of content makes it a worse place for teens specifically (plus the extreme prevalence of filters, so everyone on TikTok looks "better" than their real life version)