According to one thought "If you can't explain anything simply that means you don't understand it"
Does that mean we human beings don't certainly know about god also?
What's Hinduism's views on above saying ?
human beings don't know about god am I right?
See what Kena-Upanishad says about your question.
यस्यमतं तस्य मतं मतं यस्य न वेद स:।
अविज्ञातं विजानतां विज्ञातमविजानताम ॥3॥
YasyaMatam Tasya Matam Matam Yasya na Ved sa
AvigyanTam Vijanatam VigyanTaMaVijanaTam
He who thinks he does not know It, knows It. He who thinks he knows It, does not know It. The true knowers think they can never know It (because of Its infinitude), while the ignorant think they know It.
Kena-Upanishad Khand -2 ,Shloka 3
This verse brings out how we struggle with difficulties of human expression and insufficiency of mental utterance. By this text the teacher confirms the idea that Brahman is unthinkable, because it is unconditioned. Therefore he says: He who considers It beyond thought, beyond sense perception, beyond mind and speech, he alone has a true understanding of Brahman.
Use of the verb "know" is contradictory with "belief". God was (and is) a part of believe system even in the time of ramayana. That's why the words "theist" or "atheist" (nastik) appeared in the texts. If there exists an word for atheists in texts it means God has always been part of a "belief system".
Like a knowledge a belief system is also explainable and aggreable. Often the term understandable is used to refer aggreable and convincible. So those who can explain god believes (understands) w.r.t. those who also believes (simple).
Those who believes (read understands) but fails to convince (read explain) others don't understand (read have enough convincing power) as the previous case.
And those who don't believe (read understand) don't bother to convince (read explain) others.