I actually see more unique champs in my ranked games nowadays. Also, why would you care if people are playing those champs or prioritizing them? Why are you complaining and not abusing that fact. You can abuse this and find unique champs that you know how to play that aren't meta and do well against those match ups or are more influential in a game than they are.
I play Rek'sai Jg and Orianna midlane. So far i'm 5-0 Orianna (just started playing her a week ago), and I now know how stupid she is if played correctly.
The point here is, who cares if other people pick those champs.... look for champs who look like they might be extremely influential and play those. You'll actually be more respected in ranked for not following the meta while picking 'VALID' champs (not teemo) and 80% of the time, those champs are WAY better than the ones listed here. Trust me. I've also been playing alot of viktor and he's also pretty busted.
Let me give you a list of champs that I think are influential yet are not in the 'meta':
(Just got buffed)
(1 Shot potential is real, also the wall to catch people out, so much area control. It's like the new azir (control mages are best in soloq, forget about any assassins))
Looking at either brand mid or support, dumb champ with high damage.
Probably the best ADC to carry due to the easiness of CS'ing early game and getting that gold to spike up. Long range and plays safe. Also considered one of those "Control champions" who control area's with traps)
Have you seen hauntzer play these champs? Titanic hydra op.
Look at Arcsecond and how he plays this champion. He didn't get #1 in challenger with 'meta picks'
Frozen Mallet still busted on him. Played him on another account few days ago. Very influential in split AND teamfight
More champs that I didn't want to give a description for because i'm tired, but I still believe these champs can easily carry.
All these champs have the potential to carry even harder than those champs that you have listed which are considered 'meta' if played correctly. You just have to know the universal rules and basics of league of legends, and atleast a 1 week experience playing the champs first to understand them and get a feel.
In conclusion, it does not matter if there are only 20/150 champs being played. There are many champions who are even stronger than those, but people refuse to play them either because they are 'boring', they are a 'tank' (Why don't people play tanks? Defensive stats are still combat stats, not only damage), or they just refuse to play non-meta champs because of their role-models/streamers.