Oh i can explain that low start, cause there is a very good reason to start low
5x5 is a full compound schedule. It means you train the entire body each time. Because of this you can only do them 3x/week if you really press ahead, cause you need a recovery day.
TO become stronger, your body needs to learn how to work togheter. Tendon and muscles that connect different groups must get stronger, the neural system must improve coordination under increasing stress, muscle explosiveness must increase, mechanics must increase..
You allways start on the low side on these schedules, because you can fully focus on the movements, your body adapts to the training type.
2 weeks in your muscles should be fully adapted
3 weeks in you should start to feel improvement
and the 4th week is basically your previous max allready, meaning week 5 and 6 are about improving.
Starting lower means you have alot of progression ahead of you, wich is one of the core mechanics of these schedules
I'm currently doing an ed coan deadlift routine. My deadlift is at 275 kg and i got a projected in training max of 290 and on comp max of 300.
First of 10 weeks ended with 2*220kg. And i am fucking happy for that, because it means i could focus alot on good form and movement and feel you got loads of progress left in the tank. 2 weeks from tomorrow i'm supposed to pull 2x260, wich might be a huge grind.
When you have run these schedules for a few times, you'll learn to appreciate "starting low"