I've noticed people like to say things are "complicated" when "things" make their side look bad. In these cases, people don't like simplicity. They want to "complicate" things to rationalize the situation.
Some Northerners did hate Blacks. Some pitied them. Some sympathized with them and helped them.
This is absolutely true, but very misleading. It gives no scale about how many people hated blacks and how many people pitied them and wanted to help them.
In the 1860s, The vast majority, say 90% of the Northern population hated them. Perhaps 10% pitied them and wanted to help them. These people were considered extremist kooks for their time period. They were not unlike the modern Liberal loons we see trying to normalize LGBQ+ and "transgenders" nowadays.
Many of them just didn't think of them much al all.
Especially when they had no black people around.
Even in states that "officially" forbade African-American settlement, free blacks lived without much trouble from their neighbors.
So long as they got out of town before nightfall.
"Racism" as a concept didn't really exist back then.
That's funny. They didn't have a word for it, but the actual act of being racist was all too common.
Everybody in those days was by our standards somewhat racist.
Way more racist than modern people can even comprehend.
I remember reading about Lincoln telling a joke in which someone was using a young black boy's Johnson as a razor strop. (He didn't use the words "young black boy. He used the "N" word.)
It was more blatantly a matter of race in those days, but it wasn't necessarily hatred.
Threatening to hang them or sell them into slavery sure sounds like "hate" to me.
Consider the success of Uncle Tom's Cabin, the runaway best selling novel, turned into an extremely popular play. Clearly many Northerners did have sympathy with the slaves. Many more probably didn't think about them much at all.