Am I an insignificant array? An insignificant array is an array of positive integers, where the absolute differences between consecutive elements are all smaller than or equal to 1.
For example, the following array is insignificant:
[1, 2, 3, 4, 3, 4, 5, 5, 5, 4]

Because the corresponding (absolute) differences are:
[1, 1, 1, 1, 1, 1, 0, 0, 1]

Which are all smaller than or equal to 1.

Your task is to determine whether a given array of integers is insignificant.

You may assume that the array always contains at least two elements.
Standard input and output rules apply. You may take input (and output) in any reasonable format.
Default Loopholes are forbidden.
The truthy / falsy values have to be distinct and consistent.
This is code-golf, so shortest answer in bytes wins.

Test cases

Input -> Output

[1, 2, 3, 4, 3, 4, 5, 5, 5, 4] -> true
[1, 2, 3, 4, 5, 6, 7, 8, 9, 8] -> true
[3, 3, 3, 3, 3, 3, 3]          -> true
[3, 4, 4, 4, 3, 3, 3, 4, 4, 4] -> true
[1, 2, 3, 4]                   -> true 
[5, 4, 3, 2]                   -> true 
[1, 3, 5, 7, 9, 7, 5, 3, 1]    -> false
[1, 1, 1, 2, 3, 4, 5, 6, 19]   -> false
[3, 4, 5, 6, 7, 8, 7, 5]       -> false
[1, 2, 4, 10, 18, 10, 100]     -> false
[10, 20, 30, 30, 30]           -> false

I used the values true and false.
Jelly, 3 bytes
IỊẠ

Try it online!
How?
Just the perfect challenge for Jelly.

IỊẠ   Full program.

I     Increments; Get the difference between consecutive elements.
 Ị    Insignificant; return abs(number) ≤ 1.
  Ạ   All; returns 1 if all the elements are truthy, 0 otherwise.