No that was an observation.

An observation about the argument is part of a debate, an observation about the person that is making the argument is an ad hominem.

It's literally the definition of "ad hominem."

In that regard, your defense that you were merely making an observation is irrelevant. It's relevant what you were making an observation about.

I'm not judging you for it, I don't think you're of poor character due to it.

Again irrelevant, and I don't particularly care either way what you may or may not think about me.

The relevant point is that instead of tackling the argument that was being made, you decided to instead attack my comprehension.

That's an ad hominem, an attack on the person you're having a conversation with.

I'm not complaining about that, by the way, I'm merely providing you with an explanation since you're apparently ignorant - i.e. lacking the knowledge - of what does and what doesn't constitute an ad hominem.

You, on the other hand, are the one complaining about being attacked after bringing the conversation down to a level of ad hominem attacks, and you seem to be interested in maintaining that low level of discourse by throwing in another ad hominem here.

So my suggestion to you would be: either refrain from attacking other posters and focus on the arguments they're making, or try not acting insulted when you're being treated the same way that you're treating others.