Hitler should have not even tried Operation Seelowe, but tried to strangle Britain with U-boats. He could have tried taking Egypt as well. But no way was the Operation going to be a success except by luck for many reasons.
1. The Luftwaffe needed complete Air Supremecy, and that could never be achieved. If Britain was going to lose over Southern Britain, they planned to pull back.
2. The Germans needed to cross but the RN would stop it, as well as crappy Rhine river boats to cross. Not sufficient boats, nor good as the English channel can be rough water.
3. Airborne troops could not win the Battle. The Germans had a tops 6,000 parachute soldiers ready, and tanks could not be air dropped in great numbers, leaving mainly light equipment only.
4. Logistics. The largest reason of all. If the Germans somehow got to Britain, and their soldiers survived the first British counter attack, the Germans could never supply the soldiers with enough food, ammo, equipment, or fuel to get far. They would be defeated.