A landing page is for one campaign or one offer. It has a single next step and almost no other job. A website is the place the rest of the company lives: services, proof, and a way for someone who was not in the campaign to understand you.
Sending paid traffic to the homepage usually wastes the click. Sending every visitor to a landing page usually hides the company. Use both, and make them say the same thing.
Build the page the campaign promises before you buy the traffic.