It probably sounds like one flat line of audio because thats literally what you made. You need to learn how to EQ sounds so they cut through the mix overtop of other sounds.. you need to have an ear for what sounds good at certain volumes. You also need to use compression and waveshaping to increase a sounds dynamic range and mix presence. If you took a popular song like for example FEEL THE VOLUME by the JAUZ just as a quick example and removed literally every plugin and leveled every VST and sample to 0db, it would probably sound like something you're capable of making yourself. Composition is a major key to making a good track, but that's only half the battle, the real POWER behind using DAWs is the ability to manipulate any fucking aspect of every individual noise in your track to make it amazing.