No, they won't be much quieter. The noise is a function of the shape of the propellors, their diameter and the speed of the air flowing through them. The typical drone blade has to run at 7K rpm in order to just hover the drone, 12K and up to maneuver. That's very much in the audible range and the speed with which the air flows through and the fact that the air flows downwards through them pretty much guarantees a very loud presence.

A couple of these at all times and you'll be ready to start target practice.

We should design them to have owl like wings. Owls fly very quietly.

You should definitely watch this:

https://www.youtube.com/watch?v=lVo3wEkyci4

and

https://www.youtube.com/watch?v=nnR8fDW3Ilo

Also, while birds are really good at using their wings to glide and provide propulsion flapping designs that need to lift much more than their own weight have so far not worked very well. So I don't really see them as viable for packages.

Interesting. Seems like some birds can lift a lot of weight though like a hawk carrying a rabbit.

Yes, but for a given weight in flight so far nature seems to be doing much better than batteries or fuel when it comes to carrying capacity. That's not to say that will not change, but for now biology has the edge, especially when you compound the problem such as limit the noise emitted.

True, but imagine if these drones handled food/grocery/retail delivery, the amount of cars on the road would drop immensely. As long as the tradeoff is 1 car -> 1 drone.

Trading off one car for one drone would result in a massive increase in noise. To be a win, you'd need each drone to replace hundreds or thousands of cars, and right now the equation is the other way around.

Cars are getting quieter all the time, too. Tire noise already dominates for most vehicles at city speeds, and EVs improve the picture even further. Diesel trucks are often pretty noise, but they're mild compared to a drone, and electric trucks will drastically cut down on noise.

Not to mention in most places, highways (the places where cars make the most noise) are far away or acoustically shielded from where there are people.

You’re assuming nothing else would fill the gap left. It’s not a static system.