"Hey, that's already been taxed!" does have some intuitive appeal, but honestly I think that intuition comes from the game of Tag or something.
But money, being fungible, in constant circulation, and yielding assets and profits from re-investment, has many points at which it might feel fair to tax it.
It might not feel fair, but at least there's more there to discuss.
When I die and give my home to my kid that’s not a transaction that a family home going to family.
Or are you arguing that when a husband dies the wealth should be taxed before going to the surviving spouse?
Or if you pay for your kids education (say college - they’re an adult) should that money be taxed?
That's a ridiculous point, by the way. All money is taxed repeatedly. Hand it to a store. Sales tax. Report it as profit. Corporate tax. Pay it to employees. Income tax. Hand it to a different store... There's no "moral" calculus here. We tax economic activity. If you give money to someone else, be it for a candy bar or in an inheritance, that's economics and the apropriate place for government to take a cut is on something that sales linearly with the economy.
Same also goes for taxes on real property. My land had already been taxed long before I bought it.
Do you think that all of those taxes are also immoral?