Many people trace modern conservatism to Edmund Burke, who published in the late 1700s. Burke basically said "we don't really know how things work or what we're doing, so we should be careful and slow when making changes."
This means preserving old ways of governing (parliament, constitution, elections, etc) and introducing change gradually. It also applies to handling the natural world. Don't cut down all the forests; we don't know what might happen. Don't pollute the air and water, we don't know the knock-on effects; etc.
There is very little of Burkean conservatism in the modern American republican party. What they appear to want to conserve is privileges that their group used to enjoy, privileges that equality movements have slowly eroded. And they're willing to use radical change for their benefit: end all imports, close the border, get rid of departments of energy and education, etc etc.
