Yes, climate fluctuates. Yes, there have plausibly been years of drought and fire in centuries past that would rival recent years. But absent the specific data you say is lacking, if you believe that climate science is generally correct, then more drought, more warming, more fire is the obvious trend. Not just California, but the entire world.
Regardless of whether similar events have happened in the past, there’s an obvious reason for the dramatic uptick between the 1970s and today: CO2 in the atmosphere, put there by humans.
The fact that this reason is "obvious" doesn't mean it's correct. Climate models based on the assumption that human CO2 emissions are the primary cause of warming have been significantly over-predicting warming. So I don't think we can say human CO2 emissions are the primary cause. We are still too uncertain about how the climate works for that.