Looking down on one of these engines, the large plastic part on the top is only a cover or shield that should pry right off. Under this would be a front and back valve cover, with the intake manifold in between. Your leak, if it’s showing up at this height on the engine, is more than likely going to be from a valve cover gasket, head or intake gasket. Also, depending on some variable features, your vehicle may or may not have additional oil lines or hoses serving other accessories, each which could be the source of a leak. As for the timing cover, this is located at the front off the engine (actually facing the engine from the passenger side), and is mounted vertically. I wouldn’t think an oil leak from this area would accumulate at the top area on the engine.
If you investigate further it might be helpful to take a few pictures that might be useful in getting the help you need.
Good Luck!!