They used plastic all over the place. They just didn't have plastic bottles and bags. And they used plenty of toxic chemicals and materials as well (lead, asbestos, coal, DDT--which they even sprayed on kids), threw trash all over the place, and so on, all of which caused horrific pollution that it took later generations to fix.
No they didn't. Boomers were children in the 40s, 50s and 60s. Plastic use was not nearly as widespread, it wasn't until the mid 70s that the first commercial plastic bottles came out and it was not until the mid 80s that plastic bottles were starting to be used on a scale comparable to glass in the USA and they did not have plastic in many goods. TVs, in the homes that had them, where in wooden cases and there was almost no plastic on automobiles
In terms of hard numbers, in 1960 there were 390 short tons of plastic waste produced in the USA, less than 1 ounce of plastic per person. In 2021 there was 42,000,000 short tons of plastic waste produced, over 250 lbs per person .... and we have twice as many people.
They did throw out trash everywhere, but it was mostly paper trash which is biodegradable and we did not have a huge plastic Island floating in the Pacific Ocean.
While they burned coal for energy, they used FAR LESS energy overall and burned less coal than generations that followed, including the current one. Coal use has been in decline for quite a while now and yet the US still burned 513 short tons in 2022, compared with 415 short tons in 1960. If you look beyond coal at all fossil fuels in 1960 Americans generated about 48 exajoules of energy from fossil fuels and in 2024 about 100 exojoules, roughly twice as much.
Pollutants were in widespread use, including the things you mention, and not as heavily regulated. But these cause mostly localized effects and the environmental effects, on a global scale, are not nearly as significant as those being caused by later generations.
It is simply not comparable, the current generation is doing far, far more harm to the global environment than previous generations did and not only are they destroying the planet, they actually know they are destroying it, unlike previous generations.