I can try to put it in plain English if you think it'll be confusing to a newcomer.
Before I try, let's explore how Ethereum is described by those who develop it. The home page seems as good a place as any.
https://www.ethereum.org/
Here's what the first paragraph on the homepage describes Ethereum as...
"Ethereum is a decentralized platform that runs smart contracts: applications that run exactly as programmed without any possibility of downtime, censorship, fraud or third party interference."
So even the Ethereum developers describe the core use as contracts. It doesn't strike me as a controversial idea.
How would you describe Ethereum?