AWK, 66 bytes

split($5,a,":")&&$0=((b=a[1]%12)?b:12)":"a[2](a[1]>11?" PM":" AM")

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MATL, 9 bytes

5:24)16XO

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Explanation

5:24    % Push array [5 6 ... 24]
)       % Implicit input. Get characters at those positions. This
        % removes the first four characters with the day of the week
16      % Push 16
XO      % Convert to date string format 16, which is 'HH:MM PM'
        % Implicitly display

,,,, 41 bytes

::18⊢3⊣⇆15⊢3⊣i11>"  APMM"⇆⊢2⟛↔15⊢3⊣i12%s#

Explanation

WIP

JavaScript (ES6), 69 bytes

d=>new Date(d).toLocaleString(0,{hour:n='numeric',minute:n,hour12:1})

f=
d=>new Date(d).toLocaleString(0,{hour:n='numeric',minute:n,hour12:1})
console.log(
  f('Fri Jun 30 2017 21:14:20 GMT-0700 (PDT)'),
  f('Fri Jun 30 2017 00:10:23 GMT-0700 (PDT)'),
  f('Fri Jun 30 2017 12:10:23 GMT-0700 (PDT)'),
  f('Sat Jun 31 2018 8:06:20 GMT-0700 (PDT)'),
  f('Fri Jul 01 2017 01:14:20 GMT-0700 (PDT)'),
  f('Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)'),
)

JavaScript (ES6), 58 55 bytes

Assumes you are in the United States.

d=>new Date(d).toLocaleTimeString().replace(/:.. /,' ')

f=
d=>new Date(d).toLocaleTimeString().replace(/:.. /,' ')
console.log(
  f('Fri Jun 30 2017 21:14:20 GMT-0700 (PDT)'),
  f('Fri Jun 30 2017 00:10:23 GMT-0700 (PDT)'),
  f('Fri Jun 30 2017 12:10:23 GMT-0700 (PDT)'),
  f('Sat Jun 31 2018 8:06:20 GMT-0700 (PDT)'),
  f('Fri Jul 01 2017 01:14:20 GMT-0700 (PDT)'),
  f('Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)')
)

JavaScript (ES6), 81 78 bytes

Answer before outputting a leading 0 in single-digit hours was made optional and test cases without leading 0s were added.

d=>([m,s]=d.slice(16).split`:`,`0${m%12||12}:${s} ${m<12?'A':'P'}M`.slice(-8))

f=
d=>([m,s]=d.slice(16).split`:`,`0${m%12||12}:${s} ${m<12?'A':'P'}M`.slice(-8))
console.log(
  f('Fri Jun 30 2017 21:14:20 GMT-0700 (PDT)'),
  f('Sat Jun 31 2018 08:06:20 GMT-0700 (PDT)'),
  f('Fri Jul 01 2017 01:14:20 GMT-0700 (PDT)'),
  f('Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)')
)

C#, 145 bytes

namespace System.Linq{s=>{var d=DateTime.Parse(string.Join(" ",s.Split(' ').Skip(1).Take(4)));return d.ToString("h:mm ")+(d.Hour>11?"PM":"AM");}}

Full/Formatted version:

namespace System.Linq
{
    class P
    {
        static void Main()
        {
            Func<string, string> f = s =>
            {
                var d = DateTime.Parse(string.Join(" ", s.Split(' ').Skip(1).Take(4)));

                return d.ToString("h:mm ") + (d.Hour > 11 ? "PM" : "AM");
            };

            Console.WriteLine(f("Fri Jun 30 2017 21:14:20 GMT-0700 (PDT)"));
            Console.WriteLine(f("Fri Jun 30 2017 00:10:23 GMT-0700 (PDT)"));
            Console.WriteLine(f("Fri Jun 30 2017 12:10:23 GMT-0700 (PDT)"));
            Console.WriteLine(f("Fri Jul 01 2017 01:14:20 GMT-0700 (PDT)"));
            Console.WriteLine(f("Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)"));

            Console.ReadLine();
        }
    }
}

Jelly, 43 bytes

Ḳ5ịṣ”:Ṗṁ3µV’%12‘Dµ1¦µV>11ị⁾PAµ3¦“0: M”żFṫ-7

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This is superfluously too long! That is, Jelly sucks at time manipulation.

EDIT: I'm even outgolfed by PHP!

Japt, 15 bytes

ÐU¯24)s8 r.³+SS

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12 bytes if we can assume that the time will be given in the computer's local time:

ÐU s8 r.³+SS

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Mathy approach, 40 bytes

tG5 r"^.."_<C?+Z+B:°TnZ)%CÄÃ+" {"AP"gT}M

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PHP, 42 bytes

<?=date_create($argv[1])->format('h:i A');

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05AB1E, 39 bytes

#4è':¡¨`sD11›„APès<12%>0ìR2£R)Á… :M‚øJJ

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PHP, 45 bytes

Answer improved thanks to manatwork

<?=(new DateTime($argv[1]))->format('h:i A');

First attempt:

<? $d=new DateTime($argv[1]);echo$d->format('h:i A');

Example usage through php CLI:

php d.php "Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)"

This is my first golf try.

Go, 103 bytes

func f(s*string){t,_:=time.Parse("Mon Jan 02 2006 15:04:05 MST-0700 (MST)",*s)
*s=t.Format("03:04 PM")}

Test here: https://play.golang.org/p/P1zRWGske-

V, 36 bytes

16x3wC AMÇ^0ü^1[0-2]/12WrP
ç^ä:/é0

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Hexdump:

00000000: 3136 7833 7743 2041 4d1b c75e 30fc 5e31  16x3wC AM..^0.^1
00000010: 5b30 2d32 5d2f 3132 1857 7250 0ae7 5ee4  [0-2]/12.WrP..^.
00000020: 3a2f e930                                :/.0

JavaScript (ES6), 77 bytes

Assumes that the year has 4 digits.

s=>`${([,,,h,m]=s.match(/\d./g),x=h%12||12)>9?x:'0'+x}:${m} ${'AP'[h/12|0]}M`

Test cases

let f =

s=>`${([,,,h,m]=s.match(/\d./g),x=h%12||12)>9?x:'0'+x}:${m} ${'AP'[h/12|0]}M`

console.log(f('Fri Jun 30 2017 21:14:20 GMT-0700 (PDT)')) // 09:14 PM
console.log(f('Fri Jun 30 2017 00:10:23 GMT-0700 (PDT)')) // 12:10 AM
console.log(f('Fri Jun 30 2017 12:10:23 GMT-0700 (PDT)')) // 12:10 PM
console.log(f('Sat Jun 31 2018 08:06:20 GMT-0700 (PDT)')) // 08:06 AM
console.log(f('Fri Jul 01 2017 01:14:20 GMT-0700 (PDT)')) // 01:14 AM
console.log(f('Sat Apr 10 2020 09:06:20 GMT-0700 (PDT)')) // 09:06 AM

sh + coreutils, 22 bytes

date +%I:%M\ %p -d"$1"

(If seconds are allowed, then date +%r -d"$1" suffices.)

Python 2, 66 bytes

lambda s:`int(s[15:18])%12`+s[18:21]+'  APMM'[int(s[15:18])>11::2]

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