I know that generals like Caesar and Alexander the Great were famous for fighting alongside their troops, but was it common practice for generals to do so? I assume that as the battle begun they’d want to be on a vantage point to survey it and command units, but they might’ve joined the soldiers in a critical point in battle as a morale boost (i.e. Alesia)?
Speaking for the Classical Greeks: yes, rulers and generals absolutely did fight in the front lines. Doing so was an essential part of their role as commanders. I wrote about this in more detail here.