The forgotten door
This is a Scholastic book I got around 1965-66 while in grade school.  The book is 140 pages with a drawing at the beginning of each of the 12 chapters.  I think it's cover, which is the original, is somehow more intriguing than the later releases.  The portion of the following text in quotes is the description off the back cover because it's a really good summary.  

"Who is the strange boy who can talk to animals and read people's minds?  Where does he come from?  The boy, Jon, has lost his memory and does not know.  He only knows that he has fallen through the forgotten door to the strange planet, Earth, and that he is in great danger.  Soon the family who befriends him is in great danger, too.  There is very little time left.  Jon must find the secret way back to his planet--before it's too late."

You can't help but like Jon, he's friendly, doesn't lie, is gentle and kind to animals.  In other words he sticks out like a sore thumb.  His present surroundings are familiar and not familiar, somehow not quite right.  And the other humans, he's sure they are also humans, are not like any he knows.  With the locals out alien hunting and the government getting involved, Jon is in a tight spot.  

Thomas and Mary Bean, their son Brooks, daughter Sally and dog Rascal are people that Jon senses are like his people.  They're not like the others he's been hiding from after being mistreated when he inadvertently ruins a poacher's shot at a deer and fawn.  The Beans take him in and do their best to care for him and help him as he tries to regain his memory and find his way home.

Jon can "lighten" his feet to run and leap like a deer.  He can sense thoughts and feelings and talk to animals.  His first friend is the doe he saves.  His first enemy, is the poacher.  He has never met anyone like this cruel man.  Why did this man want to kill the deer, for Jon senses that was his intention?  And for the first time Jon feels hatred.  He knows it is not like this where he comes from.  

He's hurt, scared, lost and wants to go home.  Is anyone looking for him?  Will the people back home find the forgotten door and fix it's old, broken machinery?  Will the shifting ground that exposed it cover it up again before anyone realizes he's fallen through?   Will he be rescued from the hostile world it sealed off?  And what of the family that helped him?
Juvenile fiction, Good and evil, Life on other planets, one with nature, ageless
Alexander Key