Since friction in creating a new account is so low, the only real signal about the controller of the account is their behavior on the platform. Bots trying to sell things are rampant. Advertising (including self-promotion) is seen as a kind of spam by most of Reddit.

That being said, anyone can start a subreddit. You start your own and post whatever you want, or you spend some time in the individual communities, learn their norms, learn what each one considers acceptable to post. Something completely normal in one subreddit will be completely unacceptable in another.

Comment.

Share your knowledge, experience, humour.

Do not post 'posts' / links.

You don't need to concentrate your attention anywhere in particular or to explore anything in depth. I stay away from news / politics / gaming subs even though they are my main interest until I have enough of a history / karma.

Some subs do have subreddit specific karma limits but they are many and varied.

It can be a long game, but gaming reddit with comments is easy enough so you'll pass their 'checks'.

Shows up as a brand-new user, opens by posting a link to a low-effort blog post, gets bounced.

Sounds like Reddit working as designed, TBH