I've not played Song of Silence, but from what I've heard it's closer to Total War then HoMM.

You should try Songs of Conquest, which is heavily inspired by HoMM, with some more modern mechanics and QoL. I find it simpler than HoMM in general - might be a good intro into the genre.

Also vanilla HoMM 3 is not really a great way to play the game these days. I'd say Horn of the Abyss is a must, and there are a ton of mods to improve the game. Have a look at the VCMI project if you want to dig deeper.

My favorite is HoMM 5.5, which improves 5 a lot.

There's obviously also Olden Era, which is not bad and a very approachable intro into the series. I've not played much, so my experience is too limited to comment on it.