Something I see mentioned often is "I don't have many followers, my reblog won't matter" which is untrue.
First of all, reblogging, commenting and interacting is how you start gathering your own micro community, second of all— you literally do not know how far a single reblog from you could go in the long run.
For instance, let's say you only have one person reblog from you, and that person only have one person who reblogged from them also, and so on, and somewhere ten reblogs down the line a very large blog reblogs it and boom, the post is getting more and more exposure!
You see, it does not matter if you don't have a large following so long as you cultivate a micro community with the people you do enjoy interacting daily with.
As you can see in the second picture I added, most of the reblogs were between very small groups of people, and occasionally it'll lapse into a large blog that would create a bigger reblog pool. BUT STILL. Saying that you don't have many followers and so it doesn't matter if you don't reblog is UNTRUE.
Even if someone just randomly wanders into your blog one day, it's beneficial for both sides because A. Seeing you reblog content they like might be enough for them to follow you B. They would be exposed to new content creators they didn't know previously and might also follow / reblog from them!
So yes, do not underestimate what your reblogs and words mean, just because you're not 'big' or whatever. It is not how tumblr works!!
P.S IT IS NOT CRINGE TO REBLOG 10 YEARS OLD CONTENT ON TUMBLR. YOU SEE IT. YOU LIKE IT? REBLOG IT. DOESN'T MATTER IF YOU DIG IT FROM THE DEPTHS OF HELL ITSELF. XOXO :'D <3