No, it's not normal and it's not right. This level of favouritism and this level of utter, cruel indifference to you is not normal.
From what you said scattered throughout your posts, they have been cold, uncaring and unloving towards your husband from very early on. So it looks like they are people who love their daughter and not their son. It's clear that this was outside your experience and so it took you a while to see.
About your husband. Young pets that are loved, made a fuss of and generally cared for with good boundaries grow up to be secure animals. Young pets that are ignored or given love only occasionally tend to grow up less secure and seek for attention and love from their owners desperately, even when it's obvious they won't get it. I'm afraid that young humans are rather the same. It's the ones who are loved, given good healthy boundaries and attention that grow up secure and visiting their parents from affection. The ones that are deprived, or given only occasional warmth, often keep coming back and back hoping for the acceptance and love that wasn't there in childhood. Even if they don't, most will struggle with the need for a strong family background. It really hurts when it isn't there.
It's clear that you're struggling very badly to come to terms with this, but at this point, lovely, it's your expectations that are leading you to this torment and hurt. I'm afraid that it never really stops hurting, but all you can do when you've got hopeless uncaring parents or PiLs, is accept the situation and turn your attention way from them and towards the people who do love you. It leaves an empty hole where warmth should be, but that's because of their nature, not yours. One of the hardest things to accept is that no matter how much you want someone to love you, they might not no matter what you do.
Your hurt is so clear. I hope you can find better people to build bonds with. Your husband's family are never going to be satisfying and honestly, given the amount of attention they lavish on their daughter's family you are best off keeping your baby well away from them. I can't say this strongly enough. Children know when other children are valued much more than them, and it REALLY stays. Please, protect your child from them. They hurt your husband enough. Don't let them hurt your child.