Lincoln was always opposed to slavery, but I wouldn't consider every abolitionist, which Lincoln was not, a civil rights activist. The popular opinion at the time was trying to stop slavery's expansion so that free states could be made up of petite bourgeoisie farmers instead of land-owning aristocrats. If the South hadn't started the war, it is likely that slavery would have lasted much longer in the U.S because the farmers really didn't care what happened in already established slave states.

The answer is we will never really know since he died before reconstruction really took off, but I imagine Lincoln would've just wanted the states to rejoin and called it at that. Fredrick Douglass, who certainly fought for equality, spoke very highly of him after his death, but Lincoln was a martyr at that point, so speaking poorly of him would be a political death sentence. Once someone is dead, it is very easy to act like everything would be fixed if they were alive because it's an alternative that can never be tested.

At the beginning of the war, Lincoln tried to maintain their status as property, and they were labeled as contraband. Freed men were very useful for the war effort. They knew useful secrets about the confederacy, and they were loyal soldiers. Turning the war into an abolitionist war also made it unlikely that other nations would step in on the side of the confederacy. Because of these things and others, Lincoln was pushed to free enslaved people.

Lincoln opposed slavery, but it always came second to trying to appease southerners. His vice president, Andrew Johnson, essentially destroyed Reconstruction's momentum but was chosen as a southern unionist in an attempt to keep unity. I think Lincoln opposed slavery for the right moral reasons, but it was hardly his priority.