Learned last year that people are pretty timid when it comes to trades. I'm used to multiple blockbuster trades a season in my other leagues, but I don't think any of the GAF leagues had more than like 3 trades all year. My work league even had two trades already lol
It's probably because people don't really know each other.
Also, most people (in general) just don't have a philosophy conducive to trading. Most of the trade offers I have gotten so far have been ones where the other person is clearly hoping I'm an idiot. No one is going to trade CJ Anderson straight up for Sterling Shepard after CJ's week 1.
When I propose a trade, I'm looking for a deal that I think will make both teams better or another reasonable person could think it makes both teams better. The other person might not always agree and sometimes there's not a deal to be made, but that's the goal. At the very least you should expect them to be actually starting the players you are trading away.
For example, my team is lacking WRs but is deep on RBs and mediocre on TEs, so a good trade for me is to trade either a top tier RB for a top tier WR or for two WR2's and maybe a WR3/4 with upside.
It also helps not to be too attached to any player. A lot of people get too attached to a big name player who's scoring a lot of points. Sure Antonio Brown is a great WR, but if you're starting Tim Hightower and Darren Sproles in RB, you'd be better off dealing him for RB depth and plugging in somebody mid range in his spot.
Edit: My best ever trade was dealing Doug Martin when he came off a 50 pt game followed by a 30'ish point game. I was able to get RB2 and two WR2's value on a team hurt by injuries. The other dude was trying to consolidate his depth as he pushed into the playoffs. People complained about the trade saying I gave away too much but I ended up winning the season.
