Still reading open neutral after restoring power to lights and outlets
You found a classic case of why backstabs are considered  bad news by many electricians.
When you pulled the receptacles out the connection was temporarily reconnected and the lighting is working again. As we don’t know if everything was proper to start with but is functioning now I can tell you this will normally happen again and eventually burn the wire off at the weak point.
I would suggest checking each receptacle working back towards the supply or service and if one shows properly connected and the next one away shows wrong the problem is one of those 2 points and a device can be connecting ground and neutral down stream making them work or many other reasons.
If you plan to continue using a space heater I would suggest moving to the screw connectors or pigtails as this usually happens again with a heavy load.
The point of failure is at the last working or first non working receptacle or splice.
If this bedroom has a common wall with another don’t forget there could be a receptacle on the other side of the wall in that circuit.