The concept of time dilation and its relationship to time travel can be a bit complex, so let's break it down.
Time dilation occurs due to differences in relative velocity or gravitational fields. When an object is moving at a significant fraction of the speed of light or is in a strong gravitational field, time for that object appears to pass slower relative to a stationary observer or an object in a weaker gravitational field.
To achieve significant time dilation effects, one would need to travel at extremely high speeds or be exposed to intense gravitational fields. However, as you mentioned, the human body can withstand only a limited amount of acceleration, typically around 10-15g.
At such high accelerations, the physical stresses on the human body become immense, potentially causing severe damage or even death. Therefore, it is currently not feasible for humans to travel at speeds that would result in noticeable time dilation effects.
However, it's worth mentioning that time dilation has been experimentally verified and is a well-established aspect of Einstein's theory of relativity. It has been observed in various experiments involving high-speed particles or accurate atomic clocks.
In practical terms, the time dilation effects experienced by objects moving at speeds that humans can achieve (such as in spacecraft) or in relatively weak gravitational fields (such as on Earth) are minuscule and not significant enough to enable time travel to the future in a noticeable way.
So while time dilation is a real phenomenon, the practical challenges and limitations of human biology make it unlikely for us to achieve significant time travel effects in the foreseeable future.