Champs over anything else

Time and time again I have gone for an easy tower dive, Jump under tower to finish off a low hp enemy and make an easy escape. But then the enemy will hide underneath the tower and I am unable to attack them. Is there anyway we can get something implemented where your mouse prioritizes champions over other things in this circumstance? Same with dragon. I will try to go in and kill someone fighting dragon because they are low, but I can't attack said enemy underneath the dragon. And I will die because Im just running up and attacking the dragon because I physically cannot get an AA or ability off.