Environment – Global Warming

I have always been a believer in man-made global warming until I read a bit about the subject. There are actual two opinions. But which one is the right one. The first one is the following:
We are at the end of an "interglacial" period. which means shortly before the beginning of a new Ice Age, which will probably begin in 2000-3000 and last for  a few thousand years like the last one. Within this "intermediate phase" fluctuations of up to + / - 4 ° C are completely normal and have already taken place several times in the history of evidence - before man had the capacity to blow fossil-bearing enriched CO2 into the atmosphere .

These temperature fluctuations are historically and biologically detectable (eg the growth of certain particularly temperature-sensitive plants) and have led to historical events (more frequent crop failures, particularly cold or warm winter or summer, etc). Also, the CO2 content has changed. The idea that the "global warming" only exists, since man can burn oil is a myth. That is not to say that we should not use our resources  in a sensible way. Pollution still exists. The only thing we should learn is that we do not harm primarily the earth if we mess up our environment, but us. The "big climate" will “move” completely unaffected by what we do now with our world into the next ice age in the next few thousand years.

The second theory is, of course the more known one:

Man influences the future climate with its behaviour.  The use of oil and therefore the creation of too much C02 influence the climate in a negative way. Scientific evidence has shown, that the climate in the 20^th century has changed a lot quicker, than in the past. Since man uses oil in an excessive way  - climate catastrophes have increased on a high level and will lead to a change of climate world wide in the near future.

So, what is the correct answer?