YES! Although it now happens very rarely and only happens for Steem accounts used by a community, a platform or by a developer.
I took the time to take a look at the posts currently in Trending and it seems there are at least two that did not use any bidbot at all, minnowbooster and oracle-d. Well these two have large upvote worth to start with, but some dolphins/whales/minnows have shown support on their post eventually making it's way to Trending.
Image Source: https://steemwhales.com/clean-trending/
So yeah it is still possible, although one must have the support of a whale/s and/or a platform vote like utopian-io.
A post can trend without the use of bot's but it is not that common. It has to be a well written post with maybe something controversial to get a lot of resteems to make it.
In order to make the trending page you need to have a large group of followers who have a meaningful vote. I never look at trending as it is waste of time.
Normally posts that are on trending have had some upvote bots on them. I see the trending page today there are two posts that haven't but there are self votes from two large accounts. In my mind I know a self vote isn't botting but when the one account has 2 Million SP and a vote worth $116 then it is easy to see why it is on trending.
I saw an article the other day about a trending page without bots and what it would look like. The articles at most would be around $50 ranging down to $5. A big difference.
Yeah, it can, and it happens every once in a while. It's very rare though, and it typically has to be a post that has a very high importance, or is something that everyone agrees upon and feels compelled to share and upvote.
Its very difficult to reach trending post without bots.
Because for that purpose your post has to exceptionally well written so as to attract lot of upvotes form other users.
You have a large number followings with you.
Your topic is heart touching so that everyone is attracted towards it.
You will not trend, unless you sell your soul to the bot gods.
Or you happen to be the luckiest person on steemit.