IMO:Not necessarily our senses but interact with senses or some sensing device we have built to detect something we suspect exist but our senses by themselves are incapable of detecting
ex·ist
\ig-ˈzist\
Mirriam-Webster
- : to have actual being : to be real
- : to continue to be or to live
None of the examples given meet the standard of having a existence
A rock exists, but does not live and it becomes 'no longer a rock' by chemical and physical degradation and disolution over geologic time.
Radiation exists, but was not recognized or understood until we developed methodologies to detect radiation and hypotheses/theories to explain radiation.
God exists, but is not recognized by 'nonbelievers' (atheists) until methodologies are developed to detect and evidentially demonstrate God. Believers (theists) recognize God as real regardless of evidentiary demonstration of His existence.