Hi OP - you've crammed an awful lot into 5 years! Even assuming the first two children were twins (and you don't say they were), you must have been either pregnant and the two of you must have been caring for tiny children for much of your time together. So I would say that what you're experiencing now is what most couples would be experiencing - they are probably not to do with your specific partner (unless he's proving to be useless at parenting).
In any case - yes, it's very possible for the spark to come back. Right now, you're at the coalface; for DH and me (and indeed many or most parents, I think), the early years are the most intense because your little ones need to be in someone's care all the time and they can do very little for themselves. So when they're awake, you're on the go the whole time. During that time, in many cases, the best you can do with regard to the couple relationship is keep it ticking over. From that perspective, it's good that you're still having sex and it's good to manage the odd date night if you can, but be realistic.
As your children get older, you will start to be able to carve a bit more time out for yourselves and being with your children will generally tend to become slightly less intensive and all-absorbing. That's when you will have a bit more time to focus on each other. The other couples you talk about who appear to have a spark - I'm guessing a lot of them either have older children or no children at all. I very much doubt they are all exhausted parents of tiny children! And some of the couples who I have known who have seemed to have the most spark, almost in a performative way, have been the ones who are experiencing the most serious marital difficulties - it's almost as if the insecurity is feeding a certain excited dynamic - but that is not what you want when you're parenting small children (or at all) and it's not something to aim for. (The couple I'm particularly thinking of have since split up).
So don't compare yourself with other people because their circumstances are not the same as yours and you don't always know what's going on behind closed doors. But recognise that your relationship does need occasional attention but be realistic about your expectations for now, while you’re both so busy with tiny children.