I discovered the same my first month, mostly comments from bots- yet now I am receiving a little more genuine engagement from other people and it keeps me motivated to post more and to create content that others enjoy.
As for spam, if I don't actually like the content, I scroll past it and keep looking for something that does pique my interest.
One thing I've noticed is that those with exceptionally poor spelling and grammar are likely the ones doing the most spamming.
It's been pointed out many times that Steemit is not the place to get rich quick, and in my understanding, those who spam consistently are fishing for upvotes. Why would they do this otherwise? That's beyond me. I think they spot an account with a high reputation score and decide to zoom in hoping they'll gain some curation payout from upvoting and commenting.
I do whatever I can to help others grow by giving well meaning advice in my posts and hopefully, they will read those posts and take the suggestions to heart. Who knows? Maybe, maybe not; a part of me sort of doubts it.