I have a brand new home. I can see the lines from each joist through my lino. Why is this happening? The person who installed the flooring cannot give me a reason for this.

Can't imagine floor joists would show through floor sheathing. How far apart are the joists? Brand new house or brand new to you? If brand new, have the builder look at it.

If the joist are showing through flooring the carpenter most like didn't crown the joist when they installed them or the brick piers are out of level that the girders are built on . The last thing it could be is the floor joist are over span. Mostly the way people build these day ,
The joist where not crowned which is bad. Not crown can cause humps ,dips,and a sqeaky floor. And can keep sagging over the years. One last thing , if you have trusses instead of joist it is that the building dept. let them span trusses 2' on center which is bull chit. Floor trusses should not be less than 19 3/16" on center.

Maybe the subfloor is too thin, or it was installed too tight and buckled in summer heat and humidity, if every joist doesn't show?