What you are referring to in your argument is what is called the Milankovitch theory. The theory basically says that the Earth's rotation and revolution around the Sun is affected (mostly) by four different cycles:
1. Eccentricity
The eccentricity of Earth's orbit (how stretched out it is) changes over various periods of time. The two main periods are of 100,000 years and 413,000 years. At the moment, the eccentricity is decreasing, making it such that seasons have a more equal distance from the Sun.
2. Obliquity
The tilt of Earth's axis varies over a period of 41,000 years between 22.1º and 24.5º. Earth is right now in the middle at 23.44º and decreasing, meaning that winters are getting warmer and summers are getting colder.
3. Precession
Earth's axis also revolves over a period of about 26,000 years. It's like watching a top spin: unless the top is perfectly vertical, the tip of it revolves in a small circle about the center of rotation (which is perfectly vertical). The Earth does the same thing; the effect is that seasons become milder or more extreme in different hemispheres. At the moment, the precession is giving the Southern Hemisphere more extreme weather.
4. Apsidal Precession
Earth's orbit is more elliptical than it is circular. This means that rotating the ellipse changes where the stretched areas of the ellipse are aligned (if it were circular, it would all look the same). This process is more unpredictable but happens over a 20,000 - 25,000 year period, changing the lengths of different seasons.
There are some other cycles to be aware of (such as orbital inclination) that can be found here. So, in response to your argument, yes, the Earth does cycle between heating and cooling and yes, these cycles have something to do with global warming. But, the fact of the matter is that Earth is warming at an alarming rate. The average global temperature increase of the 21st century is too great to be caused by Milankovitch cycles alone. We actually have a serious problem.
