Yeah, I don't think I remember any fading on the 2600. Certainly the logs in pitfall didn't fade in.

Color options on the 2600 are pretty slim, and even if you had enough browns to make it fade in, it'd be difficult to have two logs on the same line in different colors, and IIRC, multiple logs on screen definitely happened.

On the Genesis, several games did a transparency effect by alternating output between the sprite and the background, but the 2600 horizontal 'pixel' width is much too wide for that to be effective. And you definitely can't have two different logs on the same line where Harry can be.