> Decades and decades ago, corporations paid most of the tax. People paid very little.

Regarding corporations paying most of the tax, according to the data at FRED (b. 1947) there has never been a point at which corporate tax receipts have exceeded individual income tax receipts: https://fred.stlouisfed.org/graph/?g=CTxn

Regarding people paying very little, all taxes (the main federal types are income, payroll, corporate, excise, and "other") are ultimately paid by people: customers, employees, shareholders, etc.