The first time I remember dreaming, I was probably 3 and a half, and and it seemed they were in black and white back then. Probably switched to color between 4 and 5.
I studied the dreaming mechanism in college. The thing that made the most sense was that our brain uses dreams to "de-fragment" memory storage, so we dream more during periods of intensive learning. Babies dream almost non-stop during the first year of life, an incredibly intense learning period.
It's interesting to see how many folks have similar type dreams as me. In my younger days, repetitive work on the job would show up in a dream, and I'd wake up exhausted because I'd already put in 8 hours on the job - in my sleep.
I have the same problem when I'm sick from a cold or other virus - if the virus really has me in its grip and my head is fuzzy, any dream time is spent stuck in a mindless activity loop, and I'm trapped. Miserable feeling.
Interestingly, if I fall asleep without putting my CPAP on, and my airway starts constricting, I will dream about being in a claustrophobic space. I do not like to be without my CPAP.
I used to have the "running in wet cement" type dreams - I believe it's because during REM sleep your brain paralyzes your muscles from being able to actually move substantially, so you have that sensation in the dream that your legs are stuck.
I don't have a "recurring dream", but I have several recurring themes. In one of them, my house morphs into my parents' house, and the front and back yard sometimes have these deep holes or trenches dug into the lawn, and everyone acts like it's normal. I haven't figured out where that comes from. Freud might have a field day with that one.