No, I honestly don't believe that children see ghosts or spirits or whatever. It's a lovely idea, I'd love to believe in it.
My Granda died a few years ago. He and I were very close, we talked about anything and everything, went on days out together, I saw him almost every day for my whole life. He really was my very best friend. A week after he died, I remember saying to DH 'I've just had this sense of peace, like Granda was here with me, with his arm around me, telling me everything will be okay'. Obviously that was nonsense. I was exhausted, grief-stricken, and had had a couple of glasses of wine.
But if it was real, if he could really pop back for a visit, wouldn't he have done so again? Wouldn't he keep doing so? If ghosts were real, wouldn't they visit their loved ones instead of a strangers house, wouldn't they actually talk to their loved ones rather than just opening doors, or turning on taps, or moving hairbrushes around like the people with 'ghost stories' always claim they do?
Dead is dead. I really believe that people love on in our hearts and minds and memories. Granda is with me every single day, when I remember all the advice he gave me, everything he taught me, and I try to live my life in a way that would make him proud. So I definitely believe that our deceased live on in what they've taught us, but they're not floating around over your child's cot