When you say "would pedophilia have still been frowned upon..." I assume you mean in a timeline going backward from today. In that case, pedophilia was also frowned upon as far back as in ancient Greek/Roman times (not an immediately sourced claim: based on my understanding of reading the history of the times). Of course pederasty was practiced in those times, though there at least it was with pubescent boys. We do not, however, appear to have any sources that would directly suggest the concept of age of consent existed. Admittedly at some point this argument devolves into semantics of what is close enough the current form of "age of consent".

The first time "age of consent" surfaces as a concept similar to how it is used today is probably 1275 in Europe. Lifting from Children and Youth in History (Age of Consent Laws - STEPHEN ROBERTSON, UNIVERSITY OF SYDNEY, AUSTRALIA) also effectively copied by Wikipedia - Age of Consent (please don't ban me):

An age of consent statute first appeared in secular law in 1275 in England as part of the rape law. The statute, Westminster 1, made it a misdemeanor to "ravish" a "maiden within age," whether with or without her consent. The phrase "within age" was interpreted by jurist Sir Edward Coke as meaning the age of marriage, which at the time was 12 years of age.

The first actual age of consent laws followed a few hundred years later.

A 1576 law making it a felony to "unlawfully and carnally know and abuse any woman child under the age of 10 years" was generally interpreted as creating more severe punishments when girls were under 10 years old while retaining the lesser punishment for acts with 10- and 11-year-old girls. Jurist Sir Matthew Hale argued that the age of consent applied to 10- and 11-year-old girls, but most of England's North American colonies adopted the younger age. A small group of Italian and German states that introduced an age of consent in the 16th century also employed 12 years.

So as a concept, "age of consent" surfaced as early as the late 12th century, and flowered in the public consciousness into something worth making a law by the late 15th century (though still obviously far more relaxed than today, to be point of being disgusting by today's standards).

That said, don't think the US was somehow immediately better about the age of consent. As late as 1880, age of consent ranged from 7 in Delaware, 10 in most states, and 12 in 9 other states + DC.

Disclaimer: I'm by no means any sort of professional historian. Just some dude on the internet who was interested by your question and looked into it a bit, especially since no one else had provided an answer.