Try not to be too concerned
All babies are different, my little girl sits up really well and likes to stand with support but she hasn’t crawled yet or even attempted too and doesn’t roll front to back, she babbles some days and not at all others ❤️ try not to worry
Update: he pulled himself to standing today for the first time so he's obviously focusing on this more than babbling or sitting up at the moment, hopefully he'll catch up soon ❤
Every child is different and he will slowly but surely start babbling wen time is right