We read this to our kids from early on, they understand - there are even more lesser known Seuss books ...

His 'adult' "The 7 Lady Godivas' with, shock! nudity ....

https://www.brainpickings.org/2012/03/02/dr-seuss-seven-lady...

And my favourite - 'The Kings Stilts':

https://www.amazon.com/Kings-Stilts-Classic-Seuss/dp/0394800...