Your premise simply isn’t true. Privacy as a concept did exist, including in the law, for example in connection with correspondence and diaries. If you read those materials from that time, you’ll see that they were in many cases far more intimate than what you might find in an iPhone today. (People used to record their private thoughts in their papers. Today, people usually don’t leave a record of things that they were thinking but never communicated to someone else.) People also had private financial and legal records, as they do today.

And the 4th amendment did protect those things. But those protections also had limits. The police couldn’t get your diary from your desk without a warrant. But they were entitled to it with a proper warrant. The fact that you recorded your deepest thoughts and intimate affairs on a phone rather than a dairy or private correspondence shouldn’t change that.

note that the interception of most correspondence, e.g. mail, is still a federal offence. additionally, the record of that correspondence can easily be erased. no warrant exists to recover the contents of a burnt letter, i.e., compel someone to testify against themselves.

additionally, one would have to prove an entry in a diary was written by the person that allegedly wrote it. or even that it was owned by that person.

i feel you’re being disingenuous with regard to how much of our lives get recorded, either directly or implicitly, on our devices. concerns on this level simply didn’t exist. giving law enforcement access to your phone is allowing for some level of intrusion into your mind.

i doubt the founding fathers were thinking about how your strava runs could be used to “testify” against yourself, if you happened to be in the wrong place at the wrong time.