Hello,
Very good question.
I believe both are needed to find a trading strategy or edge. I believe a trader needs to have an idea how he/she wants to trade and use historical price data to practice that edge for simplicity and profitability.
It sounds tedious but I believe putting a few indicators on a chart and watching the price action for a few months and writing down trading ideas, then back test those trading ideas is the best way to go.
So, you want to do 2 things, 1) think of a trading idea 2) verify the trading idea. Do 1 and 2, till you find something profitable over X amount historical trades. I think this is the best route. It will give you confidence as well.
Also, I am learning to believe an edge in the market is also protecting your cash flow or capital. From my own experiences, trading paper would have prevented many unnecessary losses that I made simply cause I didn't know what I was doing. What I mean is, you can have the best trading strategy in the world, but if you have loss all your money making many many mistakes, then you can't make money with that strategy. Take your time. No rush and enjoy this.
You may just get a row of lucky trades which "confirms" your trading idea but its not the case.
Any trading ideas should have right premises what I consider the most difficult thing as efficient market leaves tiny opportunity to discover any patterns which were not discovered by others