Actually: we are using a graph that shows rising temperatures to say that the Earth is currently heating up.
Since we are not looking for billion-year trending, data that old wouldn't be useful to the discussion it hand... not to mention that the data isn't available in any precise form.
Not taking perspective of the 1000 years (though only the last 400 are probably close to accurate) and putting it into billion year trending or even million year trending would be completely ignorant.
Using a normal warming or cooling cycle to push one's agenda is rather manipulative and disgusting.
Please look at the bolded part of your post. This again just clarifies the view that we really don't have a clue as to how this possible trend fits into the whole scheme of things. Without having a broad baseline of data, the small snapshot of data is somewhat useless.