Is there some idiom for telling someone specialised knowledge is not required to understand the situation? [closed]

I’m searching for an idiom that would mean the following: The situation is obvious to an untrained eye.

For example, say someone looked unwell, perhaps with a cold and one person says to another about a third party,

"You don’t require a doctor to understand that he has a cold, because it’s ____________ [obvious to an untrained eye as to what is going on]".

Thank you!

It's not rocket science
or
It's not brain surgery

These are often used when someone is trying to make something more difficult than it really is.

From the OED:

brain surgery n. surgery performed on the brain, neurosurgery; (hence humorously) something requiring a high level of intelligence or expertise (frequently in negative constructions, implying that something is not difficult); cf. rocket science n. at rocket n.5

rocket science n. (a) the science of rockets and rocket propulsion; (b) colloq. something requiring a high level of intelligence or expertise; frequently in negative constructions, implying that something is relatively simple.

One such idiom is: no-brainer.

"You don’t require a doctor to understand that he has a cold, because it’s a no-brainer".

TFD(idioms):

no-brainer
n. an easy question that takes no thinking to answer; a simple problem that requires no intellect to solve; a dilemma that requires no pondering to resolve.

McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

I propose common sense. It has a generally positive connotation.

common sense

n. Sound judgment not based on specialized knowledge.

^{American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved from https://www.thefreedictionary.com/common+sense}

Any Fool

In England this is an idiomatic expression for "a person with the minimum level of skill and knowledge that everyone should have".

Any fool can see..

• You don’t require a doctor to understand that he has a cold, any fool can see that
• Any fool can see he has a cold, you don't need to be a brain surgeon.

Any fool knows...

• Any fool knows you have to turn it on first

Any fool can...

• Any fool can hit his thumb with a hammer, but it takes someone special to hit his head.

1. It's easy as ABC.

Source : idioms.thefreedictionary.com (note the word intuitive.)