Are Wheat Pennies Bronze?

I think that we call them copper pennies because they are 95% copper. We know that they are not 100% copper but it is the majority that counts. Technically, silver coins are only 90% silver but we still call them silver. Personally, I like the sound of "copper" better than "bronze" or "brass". I think of bronze and brass as used for other purposes (not coins) and copper for coins.

Original Large Cents were made of pure copper, at least as pure as the technology of the late 1700's and early part of the 1800's allowed.

Small Cents were originally a copper-nickel alloy, accounting for the whiter composition of the Flying Eagle and early Indian Head cents.

During the Civil War Indian Head cents were changed to Bronze, which is an alloy of Copper and tin and sometimes includes zinc in small amounts. This alloy stayed when Lincoln (Wheat) cents came around and was retained the entire run other than the 1943 steel cents and a minor difference in 1944-1946 due to WW2.

In 1962 the composition was changed to Brass, which is very similar to Bronze but uses zinc as the hardener instead of tin.

The various bronze and brass cents were composed of 95% copper and 5% tin and or zinc.

In 1982 the cent was changed to mostly zinc but coated with copper. This remains today.

The 1944 - 46 cents are also technically brass as well as they contained no tin. The 1942 cents were also technically bronze because they did contain tin but but just the merest trace. The mint used just 50 pounds of tin for the entire 6,494,510 pounds of 1942 wheat cents produced. Normally that amount of tin would have only produced 5,000 pounds of cents. (The law required the cent alloy to be 95% copper an 5% tin and zinc, but did not specify the exact proportions of tin and zinc. They had ben reducing the amount of tin all through 1941. In 1942 with tin on the restricted list the mint was not allowed any so they made do with the 50 pounds they still had.)

Shell case cents are a highly-debated, controversial topic. There is actually no concrete proof the mint used shell cases in a volume worth mentioning. Based on what I've read over the years, I suspect only a very small amount of casings (10's of pounds) were used mainly as a publicity stunt.

I already knew that early large cents were (relatively) pure copper, but I never understood why. Maybe it was the desire to be taken seriously as a nation (avoid accusations of debasing their small denominations of currency,) but humans have known for thousands of years that pure copper isn't a very useful metal. That's why the "copper age" was extemely short and localized until bronze was invented, leading to the much more lengthy and global Bronze Age. I suppose the early cents held up against circulation alright, but it surprises me that we didn't switch to bronze at least after the Lousiana Purchase in 1804.

That's what they did for the 1944 - 46 cents, melted the shellcases and added extra copper to bring the alloy up to 95% copper 5% zinc. The shell cases were actually a real headache for the Army because they didn't know what to do with them. They couldn't get anyone to accept them for recycling due to the possiblity of live shells being mixed in. Standard procedure was to just bury them but they were afraid that could be a public relations disaster with all the material rationing and the scrap drives being encouraged. The Mint agreed to accept them if the Army searched them first to make sure no live shells were in them.

Brass is or supposed to be Copper of about 89%, Tin of about 1% and Zinc of about 30%. I use the term about due to there are numerous items made of so called Brass where the amounts of those metals varies.
Bronze is also Copper and Tin and various other materials such as Phosphorus, Manganese, Aluminum, Silicon, etc. The massive variations in what is called Bronze is done to create different results. For use in weapons during the Bronze age, almost anything was added to make the weapons stronger.
In coinage, as already well noted in this post, most people just say Copper. Since the US Mint does not actually make the Copper sheets used to make coins, any variations in percentages are possible.