Why won't my MacBook update with plenty of storage?

Why won't my MacBook update even though I have plenty of storage and contains no extra apps, softwares, or excessive amounts of files, photos, or messages?I have 2TB of storage for the 3 apple devices I own, my iPhone, iPad 6th Gen., and MacBook Air 2016. With all three devices I've only used up 97.5GB yet my MacBook repeatedly states that I do not have enough disk space and need "at least 16GB available".