Add Sancho and start comparing the XI & the bench to Liverpool's based on the current level & impact. Let's see if you'll understand.
Let's look at the stats of the attackers this season in th
Rashford - 14 goals 6 assist in 22 games
Mane - 14 goals 9 assists in 26 games
Martial - 11 goals 3 assist in 23 games
Firmino - 8 goals 7 assists in 29 games
Sancho - 17 goals 17 assists in 27 games (Holy shit!!)
Salah -16 goals 6 assists in 26 games
These stats are only from the premier league and Bundesliga and as you can see our attack which is young and can only get better matches up to theirs. The Bundesliga has obviously caused Sancho's stats to skyrocket but I'm not going to use that to reduce his quality as a player. If you like you can take away 10 g+a contributions from Sancho to make it fairer and it still matches up
On our midfield I'd say Liverpool has a midfield trio that perfectly suits their system. But we can't judge Bruno Pogba and Fred trio because we haven't seen them. However pick them out individually and our midfield is superior to theirs
On defence only Van Dijk and Robertson is better than what we have in our starting line up. Our RB is the best in defense and theirs is the best in attack. And Maguire is the better than their 2nd CB. Overall though I'd say their defense is better
It's hard to compare the bench but I'll give you this one and say Liverpool's is slightly better even though I'm not so sure tbh
Overall Liverpool is better but we can't say it's impossible to challenge them for the title when our squad plus Sancho is almost as good as theirs