Help on choosing my first DSLR?

Hello, I wanted to purchase a new DSLR under $1000, Ive had my eye on mostly the Cannon T6, T6S as well as the Nikon D3300. Im still a bit confused on when people say the lense is more important than the megapixels (aside from user skill) because Im so used to using cell phone cameras and what not. The main things I want to use it for is landscape and night time shooting. I always just assumed if there are more megapixels there would be more detail. I have some existing lenses from my dad for Cannon, but since this is my first time buying im not sure for the price if its better to stick with cannon or jump ship if Nikon is the better route for the price. Thanks:)

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