My eldest was like this. Didn't sleep through until six, spent all day watching intently, taking everything in screaming because she was so tired with no napping. She's now 12, and very bright, into all sorts of activities, plays music at a pretty high standard (two instruments and voice), loves sports, loves making things, is very sociable etc. She is still very intense and full-on. DH and I have a catchphrase, said in a cheesy German/Euro accent "Maximum DD" when we ask one another how their day was. She's amazing, but exhausting, IYKWIM. Goes through life being picked for everything, winning all the prizes, dancing to her own tune.
Our second was the kind of baby that you put down, they smile and fall asleep, woke up smiling and gurgling, happy to play quietly or watch me do things. Napped well from the start. He's a thinker now, but so much less intense, and happy to be part of the pack, not noticed, conforming in every way.
Interestingly, now DD has been at secondary school a year, and he's been on his own in their primary school, he has started to come out of his shell far more, and has grown enormously I'm confidence, but this could also be age-related, as he has matured so much this year (he's 9 now).
Alert babies are amazing, OP- enjoy yours. I know it's such hard work, but the fire and intensity from them is amazing. I remember a family friend meeting DD for the first time, when she was 10 days old. He said: "Bloody hell, it's like there's a real person in there!"
He's only come across baby-type babies before
it was a bit of a shock for him...and then his second was an alert one!