Absolutely it might be a racism issue, but I don’t think anyone can determine that from what you’ve written.
What does seem to be at issue is a difference in expectations around what neighbours are and how they are supposed to behave and react. There may well be a cultural element to that but there may not. All people are different no matter whether they share a race or culture, and what some may see as lovely, friendly, neighbourly behaviour, others might see as incredibly overwhelming and pushy.
Personally, while I rather like my neighbour on one side of us, and we will keep an eye out on each other’s houses and such when away, take in post, and I’ve cut her lawn once or twice; I still do my best to avoid talking to her as she is retired and has no sense of time or that I might be in a rush and will happily keep me balancing a baby and bags of shopping on my front path while she chats away incessantly for ages. She takes no heed of my, ‘well I must get on…’s and such.
Neighbours on my other side or across the road might say hello once in a while, but I couldn’t tell you their names even. And I don’t think that’s particularly unusual. Back in my grandparents’ day they’d have known have the street quite well, but nowadays it’s not really a thing.
I’d find an invitation to dinner from a neighbour nice but a bit odd, and would be frantically thinking up excuses. I’d find having you turn up with food incredibly pushy and rather weird.
You can’t force friendships. Most people, especially by the time they have kids and stressful jobs and such, aren’t desperately seeking out friendships. I’ve been invited to dinner with colleagues and such and several occasions and, even if the evening was very lovely, unless there was an amazing coming together of mids and a great friendship was formed, I’m probably not going to go out of my way to build on that. Maybe once in a while, but it’s hardly going to be a life changing thing. I’m too busy and I’m perfectly happy with my circle and family. I might see another school mum if it’s a play date or something, and a coffee and chat will be nice, but I’m there because of our children.
It sounds rather, from your post, like you’re trying to build a community and have everyone popping in and out of each other’s houses and spending significant amounts of time with each other. I doubt even if they do like you, anyone else is massively up for such a full on thing.
As for the other neighbours’ children, they go to the same school so that’s a connection that your children lack.
Incidentally, there was another post on here some weeks ago when the OP was asking how to (politely) tell their neighbour to back off as they kept bringing food over and such, and while it was lovely the first time, it wasn’t wanted and felt completely overwhelming. I do wonder…