Both $CO_2$ concentrations and temperature have been much higher than current levels. In fact, the average $CO_2$ concentrations and temperature for the Earth were higher than they are today.
Earth's Temperature and $CO_2$ history:
None of those lead to a "run-away" or "point of no return" climate events - let alone turning the planet into one like Venus. Most likely, now is no different from then.
From a controls perspective, the fact that the Earth's climate has remained relatively stable over billions of years is very strong evidence that the climate system over all is a negative feedback loop (meaning it is stable).
The alternative (and this is another strong possibility) is that the Earth's climate is really metastable. Meaning, the Earth's climate will tend to return to its current baseline even if you introduce events to push it away from its normal climate.
However, if you push hard enough on one climate parameter (e.g. introducing more $CO_2$) the Earth's climate will eventually go through a transition to a new metastable state (probably a higher temperature).
Earth Climate is likely Metastable:
Current state of the art climate models disagree with measurements and each other on what might cause the transition to a new state AND what temperature that new state might be the new average.
Although human activity could cause an undesired warming of the Earth is certainly possible (even likely), there's no way for human activity to cause the Earth to become Venus like in the current era. However, within 1.6-2.5 billion years, the gradually brightening Sun will warm the Earth enough to evaporate ocean water leading to a run-away greenhouse. The Earth will reach this tipping point regardless of what humanity does.
Something even scarier
In the Earth's ancient past (2+ billion years ago), the Earth's surface chemistry transitioned from a reducing atmosphere (e.g. Methane dominant) to an oxidizing atmosphere (e.g. Oxygen dominant). This killed most life on the planet.
Free oxygen is toxic to obligate anaerobic organisms, and the rising
concentrations may have wiped out most of the Earth's anaerobic
inhabitants at the time. Cyanobacteria were therefore responsible for
one of the most significant extinction events in Earth's history.
Changing the fundamental chemistry of the planet's surface would be far scarier and more dangerous to the human race than an increase in a couple of degrees of temperature.
Fortunately, we see no evidence of this happening during the current era.
The Oxygen environment biology has access to much more energy than the organisms evolved for the reducing atmosphere. The dominance of Aerobic organisms creates a strong feedback loops among life forms help stabilize the system and ensure that as long as Earth teams with life that life will work to ensure we don't seen another event like the Oxygen Catastrophe.